Human implantable tissue expanders

ABSTRACT

Human implantable tissue expanders are provided, that comprise an inner foam filling enclosed within a substantially non-stretchable resilient expansion restricting layer configured to retain a shape and/or volume of said foam filling upon changes of ambient pressure and/or temperature, and an outer shell comprising one or more layers formed of a resilient material.

RELATED APPLICATION DATA

This application is the U.S. National Stage of International ApplicationNo. PCT/IL2014/050097 filed Jan. 29, 2014, which claims the benefit ofU.S. Provisional Patent Application No. 61/758,286 filed Jan. 30, 2013,and U.S. Provisional Patent Application No. 61/781,158 filed Mar. 14,2013. Each of the foregoing applications is hereby incorporated byreference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to human implantable tissue expanders,suitable, inter alia, for augmentation or reconstruction of breast,pectorals, calf muscles and other soft tissue defects.

BACKGROUND OF THE INVENTION

Soft-tissue implants are used in various locations in the human body.The most common use is for reconstructing or improving the normal bodycontour or augmenting the female breast. The most common breastprostheses generally include a flexible elastomeric shell or envelope,typically made of silicone, which is filled with a soft gel, mainlysilicone gel, a saline solution or a combination of both.

U.S. Pat. No. 3,683,424 discloses a compound prosthesis that has anelastic sack or envelope which contains an open-cells foam core and aquantity of a liquid in the cells of the core. The envelope has aflexible tube for adding the liquid at time of implantation so the sizeof the implant can be adjusted as desired.

U.S. Pat. No. 4,298,998 discloses a breast prosthesis claiming toovercome the tightness and contracture of the fibrous capsule whichforms around an existing prosthesis. The construction of the prosthesiscauses the capsule to form at a predetermined, controlled distance fromthe surface thereof. This prosthesis is constructed with a first phaseor outer temporary component and a second phase or inner permanentcomponent. The inner component is a container or sac of a flexible,non-absorbable material filled with a fluid or gel filler material. Thetemporary outer component is an outer container or cover of a materialwhich is absorbable under the conditions of use, and an inert fillermaterial, preferably an absorbable, biologically acceptable liquid, e.g.saline solution, filling the space between the inner and outercomponents.

U.S. Pat. No. 4,650,487 discloses a surgically implantable, multi-lumen,high profile mammary implant which includes a first, flexible, elasticlumen at least partly filled with a soft gel material and having a frontwall approximating the shape of a human breast and a second, firmer,flexible lumen within the first lumen and connected thereto solely atthe rear wall of the first lumen. A third lumen preferably inflatablesurrounds the first lumen and is inflated with saline solution.

U.S. Pat. No. 5,236,454 discloses an implantable stacked breastprosthesis comprising two or more separate chambers stacked on eachother, and fastened together eccentrically, so as to give a normalcontour to the reconstructed or augmented breast and to prevent slippageof the chambers. At least one of the chambers is collapsed and may bevariably filled with liquid.

U.S. Pat. No. 5,358,521 discloses a multi-layer prosthesis thatsimulates tissue tactility by structuring the plurality of layers ofmaterial making up the prosthesis to include lubricant coating betweenthe layers. It is the plurality of layers and the lubricity of theirmovement which contributes greatly to the tactile simulation of humantissue. Present in the prosthesis is a ballast lumen which moves freelyand contributes mass and motility to the prosthesis.

U.S. Pat. No. 5,376,117 discloses breast prostheses for subcutaneousimplantation for breast augmentation. The prostheses include an outershell having a smooth non-porous outer envelope and a non-woven porousouter layer affixed to the envelope.

U.S. Pat. No. 5,437,824 discloses a breast prosthesis for implantationbeneath the skin. In one preferred embodiment the prosthesis has anouter elastic shell which encloses a biocompatible fluid and a siliconefoam insert of unitary construction having the shape and approximateconsistency and tactility of breast tissue. The foam insert occupiessubstantially the entire volume enclosed by the shell of the implantableprosthesis and consists of a foam body that is molded to the shape ofthe breast. In another preferred embodiment only a portion of the volumeenclosed by the cell is occupied by the foam insert. In yet anotherembodiment a foam insert comprising an open-cell and closed-cell foambody may directly implanted beneath the skin for breast augmentation orreconstruction without a shell.

U.S. Pat. No. 5,824,081 discloses a tissue implant having visco-elasticcharacteristics which simulate the natural tissue that is intended to beaugmented or replaced. The implant is comprised of a shell or envelopeenclosing a compound foam body and a fluid filler material.

U.S. Pat. No. 6,187,043 discloses an implant and coverings for animplant for use in the human body. Coverings for implants areconstructed to present a biocompatible surface to the body and toprovide a textured surface which serves to disorganize scar tissue whichforms around the implant.

U.S. Pat. No. 6,875,233 discloses a hinging breast implant capable abeing variably sized and that includes an exterior shell and an innerbladder. The exterior shell is typically a bellows having a plurality ofpleats so that the outer size of the implant is variable so thatdifferent sizes and shapes can be obtained. The inner bladder can befilled with a suitable filling material, liquid, gas or solid. As thebladder is filled, the exterior shell expands in a manner that creates alifting effect and a ballooning effect.

U.S. Pat. No. 8,236,054 discloses an implantable soft tissue prosthesiscomprising a hollow shell formed of a flexible elastomeric envelope, theshell having an inner volume and an exterior surface, when the innervolume is filled with an elastomeric silicone tubing that is preshapedconforming to the inner volume of the shell, the prosthesis beingadapted to be surgically implanted in a human breast.

US 2002/0038147 discloses an improved permanently implantable breasttissue prosthesis comprising angularly and immutably attached base anddome envelopes wherein the base envelope is of a substantiallytriangular shape and the dome envelope is of a substantially discoidshape, each envelope having a shell defining an inner fluid containablechamber and an outer textured surface to be in direct contact withbreast tissue and a valve formed as a part of a wall in base and domeenvelopes, the valve facilitating the introduction, containment orremoval of fluid within the containable chamber of each envelope.

US 2004/0162613 discloses a cosmetic and reconstructive prosthesiscontaining a rupture indicator, which includes an external envelope ofmedical grade elastomer containing a fluid material and a biologicallycompatible chemical indicator for indicating rupture of the prosthesis,and an internal envelope of medical grade elastomer disposed within theexternal envelope, the internal envelope containing an implant fillingmaterial.

WO 2007/000756, to the inventor of the present invention, discloses,inter alia, a human implantable tissue expander comprising a flexibleenclosure for at least one material having at least one fluid flowcharacteristic; and a flexible and resilient skeleton associated withsaid flexible enclosure and being operative to maintain said flexibleenclosure in a predetermined three-dimensional configuration generallyindependently of its orientation relative to gravitational acceleration.

WO 2008/081439, to the inventor of the present invention and others,discloses, inter alia, an implantable tissue expander including aninternal skeletal element extending between a base surface and an outersurface and including at least one plurality of elongate cells extendingalong mutually generally parallel axes from the base surface to theouter surface and being defined by elongate cell walls formed of aresilient material; and a sealed enclosure, sealing the internalskeletal element and adapted for preventing body fluids from filling theplurality of elongate cells.

WO 2010/049926, to the inventor of the present invention, discloses,inter alia, a reconstructive breast prosthesis suitable for implantationinto a void in a breast following a lumpectomy procedure in which a bodyof tissue is excised from the breast, the reconstructive breastprosthesis including an implant body at least generally configured toassume an implant shape corresponding to the shape of the body of tissueexcised from the breast and an implant shape retaining structure adaptedto maintain the implant body in the implant shape, the reconstructivebreast prosthesis having an overall density which is less than thedensity of the body of tissue excised from the breast.

There still remains a need for improved implantable tissue expanders.

SUMMARY OF THE INVENTION

The present invention provides, according to some embodiments, humanimplantable tissue expanders comprising an inner foam filling enclosedwithin an expansion restricting layer that can be made of substantiallynon-stretchable mesh or a sheet of material, and further within a shellcomposed of one or more layers. The foam filling is typicallyclosed-cell foam. Upon changes of surrounding pressure, for example atlow ambient pressure, a foam filling may expand and its shape and volumemay be altered. Tissue expanders according to embodiments of the presentinvention comprise a substantially non-stretchable layer that isconfigured to prevent such undesired expansion. In addition, tissueexpanders according to embodiments of the present invention compriseseveral features intended to confer natural tactility to the implant.The tissue expanders disclosed herein may find use in the augmentationand/or reconstruction of various soft tissues, including breast,pectorals, calf muscles etc.

According to one aspect, the present invention provides a humanimplantable tissue expander comprising: an inner foam filling; asubstantially non-stretchable, resilient, expansion restricting layerconfigured to retain a volume of said foam filling upon changes ofambient pressure, temperature or both; and a sealing shell comprisingone or more layers formed of a resilient material.

In some embodiments, the inner foam filling is enclosed within thesubstantially non-stretchable, resilient, expansion restricting layer,and the sealing shell is an outer shell surrounding said substantiallynon-stretchable, resilient, expansion restricting layer.

In other embodiments, the inner foam filling is enclosed within thesealing shell, and the substantially non-stretchable, resilient,expansion restricting layer is an outer layer surrounding said sealingshell.

In some embodiments, the tissue expander is substantially devoid of alubricating material. In particular, in some embodiments, the one ormore layers of the sealing shell are substantially devoid of a lubricantcoating.

In some preferred embodiments, the inner foam filling comprisesclosed-cell foam.

In some embodiments, the inner foam filling comprises a single foamelement.

In some embodiments, the inner foam filling comprises a plurality offoam elements. In some embodiments, the tissue expander comprises aplurality of foam elements, each enclosed within a substantiallynon-stretchable resilient expansion restricting layer.

In some embodiments, the tissue expander comprises a plurality of foamelements, wherein at least some of said plurality of foam elements arecollectively enclosed within a single substantially non-stretchableresilient expansion restricting layer. In some embodiments, the tissueexpander comprises a plurality of foam elements, all collectivelyenclosed within a single substantially non-stretchable resilientexpansion restricting layer.

In some embodiments, the substantially non-stretchable resilientexpansion restricting layer constitutes a distinct layer. In otherembodiments, the substantially non-stretchable resilient expansionrestricting layer is at least partially embedded in said sealing shell.

In some embodiments, the tissue expander further comprises a flexiblesealed enclosure, enclosing said foam filling. In some embodiments, theflexible sealed enclosure is the immediate layer enclosing said foamfilling, and the substantially non-stretchable resilient expansionrestricting layer is a distinct layer overlaying said flexible sealedenclosure. In other embodiments, the substantially non-stretchableresilient expansion restricting layer is at least partially embedded insaid flexible sealed enclosure.

In some embodiments, the substantially non-stretchable resilientexpansion restricting layer comprises a plurality of substantiallynon-stretchable resilient expansion restricting layers.

In some embodiments, the sealing shell comprises a first layerconfigured to define the consistency and tactility of the sealing shell,and a second layer overlaying said first layer and configured to definethe mechanical properties of said sealing shell.

In some embodiments, the one or more layers of said sealing shell are ofuniform thickness.

In some embodiments, the one or more layers of said sealing shell are ofvarying thickness.

In some embodiments, the tissue expander further comprises an internalskeleton element.

In some embodiments, the internal skeleton element comprises an array ofelongated cells extending longitudinally between a base surface and anouter surface along mutually parallel axes and being defined by elongatecell walls formed of a resilient material.

In some embodiments, the elongated cells fully extend between opposingsurfaces of the tissue expander. In other embodiments, the elongatedcells partially extend between opposing surfaces of the tissue expander.

In some embodiments, the inner foam filling substantially fills saidelongated cells.

In some embodiments, the inner foam filling extends outside the basesurface, the outer surface or both of said array of elongated cells.

In some embodiments, the internal skeleton element comprises one or moreflexible tubes.

In some embodiments, the inner foam filling substantially fills said oneor more flexible tubes.

In some embodiments, the inner foam filling further fills voids amongfolds of the flexible tubes, and between an outer wall of a tube and aninner wall of the tissue expander.

In some embodiments, the substantially non-stretchable resilientexpansion restricting layer further comprises one or more joining means,such as sutures, glue or both, configured to retain a shape and volumeof said inner foam filling upon changes of ambient pressure, temperatureor both.

In some embodiments, the tissue expander further comprises an outer meshpartially covering an outermost layer of the tissue expander.

In some embodiments, the outer mesh comprises a single mesh patch.

In some embodiments, the outer mesh comprises a plurality of meshpatches.

In some embodiments, the tissue expander further comprises a balloonconfigured to inflate upon introduction of liquid, gas or a combinationthereof into an interior thereof, and deflate upon removal of liquid,gas or a combination thereof from said interior thereof.

In some embodiments, the balloon is external to an outermost layer ofthe tissue expander.

In some embodiments, the external balloon is a distinct compartmentattached to an outermost layer of the tissue expander.

In some embodiments, the external balloon shares a common wall with anoutermost layer of the tissue expander.

In some embodiments, the balloon is internal to an innermost layerenclosing said foam filling.

In some embodiments, the internal balloon is a distinct compartmentembedded within the inner foam filling, unattached to an innermost layerenclosing said foam filling.

In some embodiments, the internal balloon is a distinct compartmentembedded within the inner foam filling and attached to an innermostlayer enclosing said foam filling.

In some embodiments, the internal balloon shares a common wall with aninnermost layer enclosing said foam filling.

In some embodiments, the internal balloon is between said substantiallynon-stretchable resilient expansion-restriction layer and an innermostlayer of said outer sealing shell.

In some embodiments, a tissue expander comprising a balloon furthercomprises a tube communicating with the interior of the balloon.

In some embodiments, a tissue expander comprising a balloon furthercomprises a valve communicating with the interior of the balloon. Thevalve according to embodiments of the present invention is configured topermit fluids to flow therethrough when in an open position, andsubstantially block fluid flow therethrough when in a closed position.When in a closed position, the valve is configured to maintain theballoon sealed.

In some embodiments, the valve is an integrated valve in the sealingshell, communicating with the interior of the balloon.

In some embodiments, the tissue expander comprises a balloon, a tubecommunicating with the interior of the balloon, and a valve connectingbetween the balloon and tube, wherein the valve is configured to allowpassage of fluids between the tube and balloon when in an open position,and substantially block passage of fluids between the tube and balloonwhen in a closed position.

In some typical embodiments, the valve is a self-sealing valve.

In some embodiment, the tissue expander comprises a device (e.g., aplate) with an identifying code configured for non-invasiveidentification of said tissue expander when implanted in a subject.

In some embodiments, a human implantable tissue expander is provided,the tissue expander comprising: an inner foam filling enclosed within aflexible sealed enclosure; a substantially non-stretchable resilientexpansion restricting layer at least partially embedded in said flexiblesealed enclosure; and an outer sealed shell comprising one or morelayers formed of a resilient material.

These and further aspects and features of the present invention willbecome apparent from the figures, detailed description and claims whichfollow.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1. A perspective view illustration of a tissue expander accordingto some embodiments of the present invention.

FIG. 2A-2D. Cross-sectional illustrations of tissue expanders accordingto some embodiments of the present invention. FIG. 2E. A perspectiveview illustration of a tissue expander according to some embodiments ofthe present invention. FIG. 2F. A cross-sectional illustration of atissue expander according to some embodiments of the present invention.FIGS. 2G-2H. Top view and cross-sectional illustrations of a tissueexpander according to some embodiments of the present invention.

FIGS. 3A-3B. Cross-sectional and cutaway top view illustrations of atissue expander according to some embodiments of the present invention.

FIGS. 4A-4B. Perspective view illustrations of skeleton elementsaccording to some embodiments of the present invention. FIG. 4C.Cross-sectional illustration of a tissue expander according to someembodiments of the present invention.

FIGS. 5A-5B. Perspective and top view illustrations of a tissue expanderto some embodiments of the present invention.

FIGS. 6A-6F. Cross-sectional illustrations of tissue expanders accordingto some embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to human implantable tissue expanders.

FIG. 1 illustrates a perspective view of a tissue expander (100)according to some embodiments of the present invention, suitable, forexample, for breast augmentation and/or reconstruction. The tissueexpanders according to embodiments of the present invention are sizedand shaped in accordance with their intended location in the human body.As illustrated in FIG. 1, in some embodiments, the implant comprises agenerally flat surface (102) at one side thereof, and a generally convexsurface (104) at another, opposing, side thereof.

A tissue implant according to embodiments of the present invention ispreferably resiliently deformable and compressible, and can be deformedor compressed to a deformed, compressed shape in which it has asubstantially reduced minimum dimension, thereby permitting insertion ofthe implant through an aperture in a cutaneous layer when the implant isin the deformed, compressed shape, and allowing the implant, by virtueof its resiliency and ability to decompress, to regain a desiredoriginal three dimensional shape when placed at a desired locationwithin the body for augmentation or reconstruction of the desired threedimensional shape of a body portion.

FIGS. 2A-2D illustrate cross-sectional side views of tissue expanders(200) according to some embodiments of the present invention, suitable,for example, for breast augmentation and/or reconstruction. FIG. 2Ashows a tissue expander (200) comprising a flat base surface (202) and aconvex outer surface (204). The tissue expander (200) has an innervolume filled with a foam filling (206) and defined by a substantiallynon-stretchable, resilient expansion restricting layer (208), such asmesh, enclosing the foam filling.

As used herein, the phrases “substantially non-stretchable expansionrestricting layer”, “substantially non-expandable expansion restrictinglayer” or simply “expansion restricting layer”, refer to a layer, suchas a mesh, that does not stretch or expand, namely elongate in anydirection or allow an increase in volume, to more than about 10%relative to its initial length or volume, preferably the expansionrestricting layer does not stretch or expand to more than about 1-5%relative to its initial surface area and preferably the expansionrestricting layer does not stretch or expand at all under pressurechanges of about −0.9 atmosphere. The expansion restricting layerdefines a fixed surface area of the foam body of the implant, preventingthe expansion of the gas in the foam-body under negative pressurechanges. According to some embodiments, the term “fixed” surface areamay refer to a constant or substantially constant surface area.

The expansion restricting layer according to embodiments of the presentinvention is formed of a biocompatible material, such as polyester,polyethylene, polyamide, Gortex®, cellophane, aluminum foil or othersknown to be used for implantation in the human body.

The expansion restricting layer may be a woven fabric, a non-wovenfabric, a knitted fabric or a sheet of material or a combination ofsuch. The expansion restricting layer may be formed of two substantiallynon-expandable sheets joined together. The expansion restricting sheetmay be meshed. A knitted or woven layer may be characterized by thethickness of the layer being uniform or varied, and also by varied oruniform pore size, thread thickness and type of threads. The expansionrestricting layer may be formed of a single piece, or multiple pieces orstrands of material in any suitable manner, including for example,weaving, injection molding, extruding, winding or wrapping. Theexpansion restricting layer may be closed to create a sealed enclosureby sewing, ultrasonic welding, gluing or other techniques known in theart.

In some embodiments, the expansion restricting layer is pre-formed, thefoam filling is inserted inside the preformed expansion restrictinglayer, and the edges of the expansion restricting layer are then sealedto form a sealed expansion restricting layer enclosing the foam filling.In other embodiments, the expansion restricting layer is formed as anouter layer of the filling.

The expansion restricting layer has typically lower elongationcapability and higher tensile strength capability compared to the otherlayers/enclosures that constitute the tissue expander according toembodiments of the present invention. In some embodiments, the expansionrestricting layer is composed of a plurality of layers. For example, amesh may compose a plurality of mesh layers.

The foam filling according to some embodiments of the present inventionis a matrix characterized by a closed-cell structure filled with gas,for example, air-filled foam. The foam filling can be produced bymethods known in the art, for example, by mixing at room temperature twodifferent biocompatible polymers, e.g. silicones, that release gas(e.g., hydrogen, oxygen or ammonia) in an exothermic reaction uponmixing thereof. The generated gas is trapped within the silicone andgenerates closed-cell foam upon curing, meaning that each pocket of gasis completely surrounded by solid material. The gas is replacedspontaneously by air until partial gas pressure equilibrium is reached.Part of the outer layer of the foam may include open cells.Additionally, in order to change the consistency of the foam bodyfilling the implant, the cured foam body or several elements of the foambody may undergo pressure modification, e.g. weight milling that causesthe transformation of some of the closed cells into open cells, thussoftening the consistency of the foam body. The density of the foamfilling when filled with gas is generally less than about 0.5 gram percubic centimeter and preferably less than about 0.3 gram per cubiccentimeter. Pore size and number of cells per unit volume are typicallydefined by manufacturing parameters, such as the curing temperature andambient pressure, and can vary according to the desired weight andconsistency of the foam filling.

The foam filling has a defined shape that corresponds to its intendedlocation within the body. The foam filling can be manufactured bymolding, cutting partial volumes from a larger foam lump and joiningthem together, or extrusion. For example, a foam filling can be preparedby mixing two parts of uncured silicone generating gas by a gas formingreaction, filling or injecting the dispersion into a mold and allowingit to cure at room temperature. The size of the cells or pores can becontrolled by changing pressure within the mold at various pressuredifferences and various time frames, where higher pressure results inthe formation of smaller cells. The size of the cells can also becontrolled by changing the temperature of the mold, where highertemperatures result in the formation of larger cells.

The illustrated foam filling (206) is shaped to include a flat basesurface and a convex outer surface. The expansion restricting layer(208) is configured to minimize configurational changes of the foamfilling, or retain the volume of the foam filling, due to changes of theinternal pressure of the gas inside the foam cells, upon changes in theambient pressure, temperature or both. For example, the expansionrestricting layer is configured to prevent an undesired expansion of thefoam filling upon a decrease of ambient pressure. The foam filling (206)illustrated in FIG. 2A comprises a single foam element thatsubstantially fills the inner volume of the tissue expander. Inalternative embodiments, exemplified in FIG. 2D, the foam filling iscomposed of a plurality of separate foam elements (206 a-d), thatcollectively fill the inner volume of the tissue expander. In theembodiment illustrated in FIG. 2D, the plurality of foam elements areenclosed within a single expansion restriction layer (208). In otherembodiments, the tissue expander comprises a plurality of expansionrestricting layers, each enclosing a single foam element out of theplurality of foam elements. In additional embodiments, some or all ofthe foam elements are glued or joined together.

The tissue expander (200) further comprises an elastomeric sealing shell(210). In the illustrated embodiment, the shell is an outer layeroverlaying the expansion restricting layer (and foam filling). In otherembodiments, the foam filling is enclosed within the sealing shell, andthe expansion restricting layer is the outer layer, surrounding thesealing shell. Thus, the expansion restricting layer according toembodiments of the present invention may constitute an outer layer or anintermediate layer.

The illustrated shell is sealed and completely encloses the foam filling(206) and expansion restricting layer (208). The illustrated shell (210)is composed of first (212) and second (214) layers, wherein the firstlayer defines the consistency and tactility of the shell and the secondlayer defines the mechanical properties of the shell. Each layer mayhave a uniform or varied thickness. In some embodiments, exemplified inFIG. 2E that shows a perspective view of a tissue expander (200), theexternal surface of the first (outer) layer has a plurality of grooves(220) constructed therein in the manufacturing process, which may havedifferent dimensions. Such grooves are advantageous, for example, whenthe shell is constructed by over molding the layers in an inverse order,where the outer layer is molded first, and the subsequent inner layersare molded over the outer layer. The grooves allow the outer layer toform the exact desired shape upon inversion of the resulting shell. Thelayers may have the same or different thickness. The number of layersand their characteristics (such as the polymers the layers are made of),typically define the consistency and tactility of the shell, andconsequently the consistency and tactility of the tissue expander.

The illustrated tissue expander (200) further comprises a flexiblesealed enclosure (216) located between the expansion restricting layer(208) and foam filling (206), enclosing the foam filling.

The expansion restricting layer (208) illustrated in FIG. 2A constitutesa distinct layer overlaying the flexible sealed enclosure (216) and foamfilling (206), and underlying the shell (210). In alternativeembodiments, the expansion restricting layer is wholly or partiallyembedded in the flexible sealed enclosure. Embedding the expansionrestricting layer in the flexible sealed enclosure may improve theconsistency and tactility of the tissue implant by softening its touch.In additional embodiments, the expansion restricting layer is wholly orpartially embedded in the shell, typically in the innermost layer of theshell. In some embodiments, an expansion restricting layer thatconstitutes a separate layer is embedded in a biocompatible polymer suchas silicone.

When the expansion restriction layer constitutes a distinct layer(rather than embedded in the flexible sealed enclosure or in one of thelayers of the outer shell), it may be affixed (for example, glued) toits immediate underlying and/or overlying layer. For gluing theexpansion restricting layer to an underlying layer, the expansionrestricting layer can be manufactured to enable the passage of gluethrough the mesh pores.

An alternative configuration is illustrated in FIG. 2B, which shows atissue expander (200) comprising a foam filling (206), an expansionrestricting layer (208) enclosing the foam filling, and a shell (210)composed of a single layer. The foam filling (206) is confined within anexpansion restricting layer envelope, without an intervening layer (orenclosure) between them.

Another alternative configuration is illustrated in FIG. 2C, which showsa tissue expander (200) comprising a foam filling (206), an expansionrestricting layer (208) enclosing the foam filling, and a shell (210)composed of two layers (212, 214). The foam filling (206) is confinedwithin an expansion restricting envelope, without an intervening layer(or enclosure) between them.

A foam filling, an expansion restricting layer surrounding the foamfilling and an optional flexible sealed enclosure can be collectivelyreferred to as the core of the tissue expander, according to someembodiments of the present invention. In some embodiments, the core iscovered by an outer shell comprising one or more layers, and fillssubstantially the entire volume of the outer shell. The core may includea skeleton element, as will be further described below.

The layers of the outer shell, as well as the flexible sealed enclosure,are typically formed of biocompatible, resilient materials, such assilicone, and manufactured by molding. Manufacturing of the outer shellmay be performed by a single-layer molding of each layer independently,followed by joining (for example gluing) the layers together.Alternatively, over-molding may be performed, where successive layersare molded one on top of the other. Dip molding using pre-formedmandrels can be used for manufacturing the outer shell, by serialdipping steps to form the layers that constitute the shell. In addition,a combination of the above methods may be used. In some embodiments, theoutermost layer of the shell is molded first, and the inner layer(s) aremolded over the external layer. The resulting shell is then turnedinside out and laid over the core containing the foam filling, expansionrestriction layer (e.g., a mesh) and optionally one or more flexiblesealed enclosures. The different components of the tissue expander maybe formed of the same or different materials.

Varying thicknesses of the layers that constitute the outer shell andevery other layer or structure of the implant according to embodimentsof the present invention can be facilitated bytransfer/compression/injection molding or any other technique usingmolds for manufacturing.

FIGS. 2F-2H illustrates alternative configurations of an implantabletissue expander according to embodiments of the present invention.

FIG. 2F illustrates a cross-sectional view of a tissue expander (200)characterized by an egg-shaped three-dimensional configuration,suitable, for example, for lumpectomy procedures. In the illustratedembodiment, the tissue expander (200) comprises an inner foam filling(206) enclosed within a flexible sealed enclosure (216) having anexpansion restricting layer (208) embedded therein. The illustratedtissue expander (200) further comprises an outer shell (210) composed offirst (212) and second (214) layers. In some embodiments, the externalsurface of second layer (214) is textured. In some embodiments, firstlayer (212) is characterized by a softer consistency compared to secondlayer (214).

FIGS. 2G-2H illustrate a tissue expander characterized by a wedge-shapedthree-dimensional configuration, suitable, for example, forsegmentectomy/quadrantectomy procedures.

FIG. 2G is a top view of the wedge-shaped tissue expander (200). Whenviewed from the top, the illustrated tissue expander (200) comprises afirst (220) and second (230) arcs at opposing ends thereof, whereinfirst arc (220) has greater width than second arc (230).

FIG. 2H is a cross-sectional view of the wedge-shaped tissue expander(200) across line IIH-IIH of FIG. 2G. When viewed from the side, theillustrated tissue expander (200) comprises a generally flat posteriorsurface (202), intended to face the chest wall and a contoured anteriorsurface (204), intended to face an overlaying breast tissue. The sideview of the illustrated tissue expander follows the natural silhouetteof the female breast, which slopes downwards to form a fuller projectionat its lower part. Contoured anterior surface (204) forms a slope suchthat one end of the tissue expander has greater thickness than theopposing end thereof. Tissue expander (200) comprises an inner foamfilling (206) enclosed within a flexible sealed enclosure (216) havingan expansion restricting layer (208) embedded therein. The illustratedtissue expander (200) further comprises an outer shell (210) composed offirst (212) and second (214) layers.

The tissue expanders according to embodiments of the present inventionmay comprise one or more internal skeleton elements.

The term “skeleton element” is used throughout to refer to an elementwhich provides structural support and optionally defines a predeterminedthree-dimensional shape of the tissue implant.

FIGS. 3A-3B respectively illustrate a cross-sectional side view and acutaway top view of a tissue expander (300) according to someembodiments of the present invention, suitable, for example, for breastaugmentation and/or reconstruction. FIGS. 3A-3B show a tissue expander(300) as illustrated in FIG. 2A, that further comprises an internalskeleton element in the form of a folded tube (318) formed of aresilient material, such as soft silicone or polyurethane. Typically,the tube is hollow and contains therein the foam filling. The foamfilling substantially fills the tube, meaning that it occupiessubstantially the entire inner volume of the tube. In some embodiments,the tube has a polygonal cross-section. In particular embodiments, thetube has a hexagonal cross-section. FIGS. 3A-3B illustrate partialsections of the hollow tube showing the foam filling (306) in the tube.Preferably, the foam filling is confined within the tube andsubstantially fills the tube. In some embodiments, the foam materialalso surrounds the tube such that it occupies voids formed between thefolds of the tube or between the external wall of the tube and an outerenclosure or mesh. The diameter of the tube may be constant or variedalong its length. The thickness of the tube wall may be constant orvaried along its length.

The illustrated tissue expander (300) comprises a flat base surface(302) and a convex outer surface (304). The tissue expander (300)comprises an inner foam filling (306) within a helical tube (318). Thehelical tube is folded so as to create an overall conical structure thatconforms to the shape and design of the tissue expander (300). The foamfilling and tube are enclosed within a flexible sealed enclosure (316),and further within a non-stretchable, resilient expansion restrictinglayer (308). The tissue expander (300) further comprises an outer shell(310) comprising two layers (312, 314).

FIGS. 4A-4B illustrate alternative forms of skeleton elements that maybe contained within a tissue expander according to some embodiments ofthe present invention.

FIG. 4A is a perspective view of a resiliently deformable skeletonelement (400) that includes an array of elongate cells (402) extendingalong mutually generally parallel axes (404) from an imaginary flat basesurface (406) to an imaginary convex outer surface (408) that is tuckedin adjacent the imaginary base surface (406). Elongate cells (402) aremutually defined by elongate cell walls (410) formed of a resilientmaterial. In the illustrated embodiment, the array of elongate cells(402) is characterized in that it includes a central cylindrical cell(412) and that elongate cell walls (410) are of generally uniformthickness. It is also characterized in that a regular pattern of partialcells (414) are located along the periphery of the array. In theillustrated embodiment, all of the partial cells (414) are identical. Inalternative embodiments, this is not necessarily the case. In yetadditional alternative embodiments, the elongate cell walls (410) neednot be of generally uniform thickness and may be of differentthicknesses and/or varying thickness.

FIG. 4B is a perspective view of a resiliently deformable skeletonelement (400) that includes an array of identical elongated cells (402),each having an hexagonal cross section, extending along mutuallygenerally parallel axes (404) from an imaginary flat base surface (406)to an imaginary convex outer surface (408), which is tucked in adjacentthe imaginary base surface (406). Elongate cells (402) are mutuallydefined by elongate cell walls (410) formed of a resilient material. Inthe illustrated embodiment, the array of elongate cells (402) ispreferably characterized in that elongate cell walls (410) are ofgenerally uniform thickness. It is also characterized in that a regularpattern of partial cells (414) are located along the periphery of thearray. In the illustrated embodiment, the partial cells (414) are notidentical.

FIG. 4C is a cross-sectional side view of a tissue expander (400)according to some embodiments of the present invention, comprising aninternal skeleton element in the form of an array of elongated cells,for example a skeleton element as shown in FIGS. 4A-B. As seen in FIG.4C, the illustrated tissue expander (400) comprises a flat base surface(422) and a convex outer surface (424). The tissue expander comprises anarray of elongate cells (402) extending along mutually generallyparallel axes (404), defined by elongated cell walls (410) formed of aresilient material.

In the illustrated embodiment, the elongated cells fully extend betweenthe base (422) and outer (424) surfaces of the tissue expander, suchthat substantially all the edges (412) of the cell walls are in contactwith the innermost layer (414) enclosing the foam filling (406). Forsimplicity, FIG. 4C presents only the innermost layer enclosing thefoam, which is, for example, a flexible sealed enclosure or an expansionrestricting layer. It is appreciated that the tissue expander includesadditional layers, such as the layers that constitute the sealing shell.In the illustrated embodiment, the foam filling (406) substantiallyfills all the cells of the skeleton element. In alternative embodiments,the foam filling fills only some of the cells. The volume and amount offoam within each cell can vary among the cells.

In alternative embodiments, the elongated cells partially extend betweenthe base and outer surfaces of the implantable tissue expander, suchthat only some (or none) of the edges of the cell walls are in contactwith the innermost layer enclosing the foam filling. According to theseembodiments, the foam filling may fill the cells and further extendoutside the cells, to fill voids between the skeleton element and aninner wall of the tissue expander.

Thus, in some embodiments, the foam filling fills the cells defined bythe cell walls and further extends outside the base surface and/or outersurface of the array of elongated cells, thus softening the touch of animplant containing a skeleton element.

The internal skeletal element may be formed of the same or differentmaterial as the other components of the tissue expander.

Additional types of skeleton elements, as well as methods for theirproduction, are described, for example, in WO 2007/000756, WO2008/081439 and WO 2010/049926.

FIGS. 5A-5B respectively illustrate a perspective view and a top view ofa tissue expander (500) according to some embodiments of the presentinvention, suitable, for example, for breast augmentation and/orreconstruction. FIGS. 5A-5B show a tissue expander (500) of the presentinvention that comprises an outer mesh (510) partially covering theexternal surface of the tissue expander. The external surface of atissue expander according to embodiments of the present invention istypically the outermost layer of the outer shell of the tissue expander.

The illustrated tissue expander (500) comprises a flat base surface(502) intended to face the chest wall, and a convex outer surface (504)intended to face breast tissue. In the illustrated embodiment, thetissue expander comprises a single mesh patch (510) at the apex of theconvex surface of the tissue expander. In alternative embodiments, theouter mesh comprises a plurality of mesh patches, at different positionson the external surface of the tissue expander and of different patchsize, patch thickness and pore size. The outer mesh may be knitted orwoven or made of a complete or meshed sheet, and made from abiocompatible material like polyester or polyamide for instance.

Following implantation of a tissue expander, connective tissue slowlygrows and surrounds the tissue expander. The presence of patches of meshon the external surface of the tissue expander facilitates tissueingrowth into the pores of the mesh, eventually forming a tissue-implantcomplex that anchors the implant to the surrounding tissues.

In a breast implant for example, an anterior mesh patch, on the convexsurface thereof, will anchor the implant to the overlaying breasttissue, thus creating a new implant-breast tissue complex that acts as asingle unit against external forces applied thereto, and mimics anatural breast to a great extent. A posterior mesh patch, on the flatsurface thereof, will anchor the implant to the chest wall, and islikely to mimic the natural breast to a lesser extent.

The tissue expanders according to embodiments of the present inventionmay comprise one or more balloons.

The term “balloon” is used throughout to refer to a flexible, sealedenclosure configured for controlled inflation and deflation,particularly after implantation of the tissue expander. The balloon isbeing inflatable upon introduction of liquid or gas into an interiorthereof, and deflatbale upon removal of liquid or gas from said interiorthereof. In some embodiments, the balloon is an external balloonattached to the outermost layer of the implant. In other embodiments,the balloon is internal. In some embodiments, an internal balloon isembedded within the foam filling. In other embodiments, an internalballoon is outside the foam filling, for example between anexpansion-restriction layer and an outer shell, attached to the innersurface of the shell.

The balloon is typically associated with a port enabling communicationto the interior of the balloon for inflation and or deflation. There aremany ports known and described in the literature and one example for aport is an integrated valve mechanism comprising a port integrated, forexample, in the shell of the implantable tissue expander and accessed bya needle through the skin. Another example is a remote valve mechanismcomprising a tube communicating with the interior of the balloon andprotruding from the tissue expander such that it is accessible to asurgeon after the tissue expander is inserted into a subject. The tubeis preferably connected to the balloon via a self-sealing valve that isincorporated into the wall of the balloon and configured to maintain theballoon sealed after the removal of the tube. The tube and valve mayfacilitate the introduction, or injection, of a filling, such as liquid,gas or a combination thereof, into the balloon, or removal of thefilling of the balloon from its interior.

Before implantation in a subject, the balloon is preferably in acollapsed, deflated form. The implantable tissue expander comprising thedeflated balloon can be temporarily and resiliently deformed andcompressed as described above in order for a surgeon to insert itthrough an aperture in a cutaneous layer of the subject.

After insertion and placement of the implantable tissue expander in adesignated location in the subject, the balloon can be inflated, namelyfilled with liquid and/or gas until a desired volume is achieved,resulting in an implantable tissue expander with an improved tissueexpansion capability. In some embodiments, when a self-sealing valve andtube are used, the tube is then preferably removed, for example, pulledout of the self-sealing valve. The balloon remains sealed by virtue ofthe self-sealing valve.

Following a certain time interval, typically when the surgeonappreciates that sufficient tissue expansion and tissue relaxation havebeen achieved, the balloon can be deflated. In some embodiments, theballoon is made from a needle-penetrable material that permits theinsertion of a needle and withdrawal of the internal filling. Accordingto these embodiments, deflation of the balloon can be performed byinserting a needle through the skin into the balloon through the balloonwall, and withdrawing the balloon filling. Upon withdrawal of thefilling, the balloon remains in a deflated, collapsed form, and the restof the implantable tissue expander, namely the foam filling enclosedwithin the layers described herein, serves as a filler of the expandedtissue. In some embodiments, where the balloon is inflated with gas, thenatural permeability of the silicone to may allow the gas to escape fromthe balloon into the surrounding tissues where it is dissolved in theinterstitial fluids and absorbed into the lymph and blood to be releasedfrom the body naturally. The loss of gas from the balloon graduallydecreases the pressure inside the balloon and leads to its deflation,thus obviating the need described above to evacuate the liquid or gasfrom the balloon after the required tissue expansion has been achieved.Using this method also allows the surgeon to remove the tube duringsurgery.

The inclusion of a balloon in a tissue expander according to embodimentsof the present invention may be particularly beneficial in primarytissue augmentation procedures, such as primary augmentation of anon-ptotic breast, with no ample skin and tissue redundancy. In suchcases, in the absence of a balloon, the pressure applied on thefoam-filled implant by the surrounding tissue may variably result in thedeformation of the implant rather than the desired augmentation of thetissue. If an inflated balloon is present, sufficient counter-pressureis applied, thereby facilitating augmentation of the tissue overlayingthe implantable tissue expander. For implantable tissue expandersintended for primary tissue augmentation, for example in primary breastaugmentation, the balloon is preferably located at the posterior surfaceof the implant, facing the chest wall. The balloon may not be needed inprocedures such as immediate reconstruction after mastectomy,replacement of an implant in a previously augmented breast, or in anaugmentation-reduction procedure (mastopexy with an implant), whereexcess skin is available.

Thus, in some embodiments, an implantable tissue expander of the presentinvention includes a first compartment filled with foam andcharacterized by a defined, pre-determined three-dimensionalconfiguration, and a second, flexible compartment comprising liquidfilling, gas filling or a combination thereof, that is configured forcontrolled inflation and deflation. The first compartment according tothese embodiments is configured for permanent support of an augmentedtissue, and the second compartment is configured for temporary tissueexpansion. It is to be understood that the term “permanent” does notindicate that the implant cannot be removed or replaced.

The size of the balloon, namely its volume at manufacturing and atinflation can vary, and is typically determined according to the typeand size of the implant.

FIGS. 6A-6B illustrate cross-sectional side views of an implantabletissue expander (600) according to some embodiments of the presentinvention, suitable, for example, for breast augmentation and/orreconstruction, which includes an external balloon (620). The balloon isillustrated in inflated (FIG. 6A) and deflated (FIG. 6B) states.

The illustrated implantable tissue expander (600) comprises a flat basesurface (602) and a convex outer surface (604) or a curved outer layer.The implantable tissue expander (600) comprises an implant inner corecomprised of inner foam filling (606) enclosed within a non-stretchableresilient expansion restricting layer (608). The implantable tissueexpander (600) further comprises an outer shell (610) comprisinggenerally at least two layers (612, 614).

In FIGS. 6A-B, the illustrated tissue expander comprises an externalballoon (620) affixed to the external surface of the outermost layer ofthe shell (614) of the implantable tissue expander, facing the flat basesurface (602) of the tissue expander.

In FIG. 6A, the balloon (620) is shown in an inflated state. The ballooncan be filled with a liquid, preferably a biocompatible liquid such assaline, or gas such as air. In the illustrated embodiments, a tube (622)is connected to the balloon via a self-sealing valve (624), such as aduck beak-type valve. The balloon (620) is preferably constructed from anon-porous, flexible, biocompatible material, such as siliconeelastomer. The balloon (620) can be over-molded on the external surfaceof the shell (614) or attached to it with an adhesive or other suitableattachment means. In alternative embodiments, the balloon and the outershell of the implant may share a common wall. For example, layer (612)enclosing the implant inner core may also constitute a wall of theballoon.

The balloon is typically shaped as an ellipsoid or elongated sphere.

The direction of expansion is generally symmetrical with the overallshape of the tissue expander, or more particularly with the shape of thefoam filling, but can in principle be different, as defined by design,medical use and manufacturing processes.

In FIG. 6B, the balloon (620) is shown in an inflated state.

FIG. 6C illustrates a cross-sectional side view of an implantable tissueexpander (600) similar to the one described in FIGS. 6A-6B, whichincludes an internal balloon (620) embedded within the foam filling. Theballoon is illustrated in an inflated state. When inflated, the balloonapplies force against the inner foam filling (606). A tube (622) isconnected to the balloon via a self-sealing valve (624), such as a duckbeak-type valve, and protrudes through the shell (610) of the tissueexpander. In some embodiments, one end of the valve is incorporated inthe wall of the balloon. Another end of the valve, configured toaccommodate the tube, is in line with the outermost layer of theimplant's shell. Upon filling of the balloon and removal of the tube,the valve self-seals and maintains the balloon sealed.

The illustrated balloon compartment (620) is a distinct compartmentwithin the implant inner core, comprised of the foam filling (606) andnon-stretchable resilient expansion restricting layer (608).

FIG. 6D illustrates another design of an implantable tissue expander(600) that contains an internal balloon as described FIG. 6C. Theillustrated design is characterized by an egg-shaped configuration, andmay be suitable for, instance, for lumpectomy procedures.

In tissue expanders according to embodiments of the present inventioncontaining an internal balloon, the balloon may constitute an internalpocket within the implant inner core, and thus restricted by thenon-stretchable resilient expansion restricting layer (608).Alternatively, as illustrated in FIGS. 6E-6F, an internal balloon may beanchored to an internal layer of the shell (612) outside thenon-stretchable resilient expansion restricting layer (608), thus notrestricted by it.

A tissue expander according to embodiments of the present invention mayfurther include a plate (not shown) with an embedded, chemically etched,or laser cut for example, code/indicator identifying the tissueexpander. The plate is preferably made of a biocompatible non magneticmaterial, such as stainless steel, or other non metallic polymers, suchas polyketones (PEEK) or ceramic materials for example, which do notinterfere with CT or MRI scans.

In some embodiments, a device, such as a plate, with an identifying codeembedded therein is placed within the tissue expander duringmanufacturing. The code may be of any alphanumeric character with anoptional additional symbol or design or any printable or designed sign.The plate can have a uniquely or non-uniquely identifying code. The codelength can vary, thus allowing representation of a unique code if chosenonce number of tissue expanders manufactured exceeds the maximalvariations in a specific code length. In some embodiments, the plate canbe visualized by available imaging techniques, including, inter alia,x-ray, ultrasound, C/T or MRI etc. In some embodiments, the code can beidentified without the need to remove the implant from the patient'sbody, thus providing a registry tool and mechanism for noninvasiveimplant identification.

In some embodiments a passive or active electronic device, such as an RF(Radio Frequency) ID chip as a non-limiting example, can be installed inthe tissue expander and used for identification of the tissue expandernoninvasively by an external device communicating with the internallyimplanted device.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingcurrent knowledge, readily modify and/or adapt for various applicationssuch specific embodiments without undue experimentation and withoutdeparting from the generic concept, and, therefore, such adaptations andmodifications should and are intended to be comprehended within themeaning and range of equivalents of the disclosed embodiments. It is tobe understood that the phraseology or terminology employed herein is forthe purpose of description and not of limitation. The means, materials,and steps for carrying out various disclosed functions may take avariety of alternative forms without departing from the invention.

The invention claimed is:
 1. A human implantable tissue expandercomprising: an inner foam filling; a substantially non-stretchableresilient expansion restricting layer configured to retain a fixedsurface area of said foam filling upon changes of ambient pressure,temperature or both; and a sealing shell comprising one or more layersformed of a resilient material, wherein said inner foam filling isenclosed within said sealing shell, and wherein said substantiallynon-stretchable resilient expansion restricting layer is an outer layersurrounding said sealing shell.
 2. The tissue expander of claim 1,wherein said inner foam filling is enclosed within said substantiallynon-stretchable resilient expansion restricting layer, and wherein saidsealing shell is an outer layer surrounding said substantiallynon-stretchable resilient expansion restricting layer.
 3. The tissueexpander of claim 1, wherein said one or more layers of said sealingshell are substantially devoid of a lubricant coating.
 4. The tissueexpander of claim 1, further comprising a flexible sealed enclosure,enclosing said foam filling, wherein said substantially non-stretchableresilient expansion restricting layer is at least partially embedded insaid flexible sealed enclosure.
 5. The tissue expander of claim 1,further comprising a device with an identifying code configured fornon-invasive identification of said tissue expander when implanted in asubject.
 6. A human implantable tissue expander comprising: an innerfoam filling; a substantially non-stretchable resilient expansionrestricting layer configured to retain a fixed surface area of said foamfilling upon changes of ambient pressure, temperature or both; and asealing shell comprising one or more layers formed of a resilientmaterial, wherein said inner foam filling comprises a plurality of foamelements, wherein at least some of said plurality of foam elements arecollectively enclosed within a single substantially non-stretchableresilient expansion restricting layer.
 7. The tissue expander of claim6, wherein each of said plurality of foam elements is independentlyenclosed within a substantially non-stretchable resilient expansionrestricting layer.
 8. The tissue expander of claim 6, wherein saidsubstantially non-stretchable resilient expansion restricting layercomprises a plurality of substantially non-stretchable resilientexpansion restricting layers.
 9. A human implantable tissue expandercomprising: an inner foam filling; a substantially non-stretchableresilient expansion restricting layer configured to retain a fixedsurface area of said foam filling upon changes of ambient pressure,temperature or both; and a sealing shell comprising one or more layersformed of a resilient material, and an internal skeleton element;wherein said internal skeleton element comprises an array of elongatedcells extending longitudinally between a base surface and an outersurface along mutually parallel axes and being defined by elongate cellwalls formed of a resilient material.
 10. A human implantable tissueexpander comprising: an inner foam filling; a substantiallynon-stretchable resilient expansion restricting layer configured toretain a fixed surface area of said foam filling upon changes of ambientpressure, temperature or both; and a sealing shell comprising one ormore layers formed of a resilient material, and an internal skeletonelement; wherein said internal skeleton element comprises one or moreflexible tubes.
 11. A human implantable tissue expander comprising: aninner foam filling; a substantially non-stretchable resilient expansionrestricting layer configured to retain a fixed surface area of said foamfilling upon changes of ambient pressure, temperature or both; and asealing shell comprising one or more layers formed of a resilientmaterial, and one or more sutures configured to retain a shape of saidinner foam filling upon changes of ambient pressure, temperature orboth.
 12. A human implantable tissue expander comprising: an inner foamfilling; a substantially non-stretchable resilient expansion restrictinglayer configured to retain a fixed surface area of said foam fillingupon changes of ambient pressure, temperature or both; and a sealingshell comprising one or more layers formed of a resilient material, andan outer mesh partially covering an outermost layer of said tissueexpander, wherein said outer mesh comprises one or more mesh patches.13. A human implantable tissue expander comprising: an inner foamfilling; a substantially non-stretchable resilient expansion restrictinglayer configured to retain a fixed surface area of said foam fillingupon changes of ambient pressure, temperature or both; and a sealingshell comprising one or more layers formed of a resilient material, anda balloon configured to inflate upon introduction of liquid, gas or acombination thereof into an interior thereof, and deflate upon removalof liquid, gas or a combination thereof from said interior thereof;wherein said balloon is external to an outermost layer of the tissueexpander.
 14. The tissue expander of claim 13, wherein said balloon isinternal to an innermost layer enclosing said foam filling.
 15. Thetissue expander of claim 13, wherein said balloon is between saidsubstantially non-stretchable resilient expansion-restriction layer andthe innermost layer of said sealing shell.
 16. The tissue expander ofclaim 13, further comprising at least one of a tube and a valvecommunicating with said interior of said balloon.